1. Field
A scroll compressor and a method for assembling a scroll compressor are disclosed herein.
2. Background
A scroll compressor is a compressor that includes a fixed scroll having a spiral wrap, and an orbiting scroll that revolves with respect to the fixed scroll, that is, a compressor in which the fixed scroll and the orbiting scroll are engaged with each other. The orbiting scroll revolves with respect to the fixed scroll, thereby reducing a volume of a compression chamber, which is formed between the fixed scroll and the orbiting scroll according to an orbiting motion of the orbiting scroll, thus increasing a pressure of a fluid, which is then discharged through a discharge hole formed in a central portion of the fixed scroll. Such a scroll compressor has a feature in which suction, compression, and a discharge of a fluid are successively performed while the orbiting scroll revolves. Accordingly, a discharge valve and a suction valve may be unnecessary in principle. Also, as a number of components of the scroll compressor is less in comparison to other types of compressor, the scroll compressor may be simplified in structure and rotate at a high speed. Also, as a variation in torque required for compression is less in comparison to other types of compressor, and suction and compression successively occur, a relatively small amount of noise and vibration may occur.
One important issue in scroll compressors is leakage and lubrication between the fixing scroll and the orbiting scroll. That is, to prevent a refrigerant from leaking between the fixed scroll and the orbiting scroll, an end of a wrap has to be closely attached to a surface of a head plate to prevent compressed refrigerant from leaking. The term “head plate” may be refer to a portion that corresponds to a main body of the fixed scroll or the orbiting scroll. That is, the head plate of the fixed scroll may be closely attached to a wrap of the orbiting scroll (hereinafter, referred to as an “orbiting wrap”), and the head plate of the orbiting scroll may be closely attached to a wrap of the fixed scroll (hereinafter, referred to as a “fixed wrap”).
On the other hand, friction resistance has to be minimized so as to allow the orbiting scroll to smoothly revolve with respect to the fixed scroll. However, the leakage may conflict with the lubrication. That is, when the end of the wrap and the surface of the head plate are strongly attached to each other, it may be advantageous with respect to leakage, however, friction may increase, increasing damage due to noise and abrasion. On the other hand, when adhesion strength is low, the friction may be reduced, however, a sealing force may decrease, increasing the leakage.
Thus, in the related art, a back pressure chamber having an intermediate pressure, which is defined as a value between a discharge pressure and a suction pressure, may be formed in or at a back surface of the orbiting scroll or the fixed scroll to solve the limitations with respect to sealing and friction reduction. That is, the back pressure chamber, which communicates with a compression chamber having an intermediate pressure of a plurality of compression chambers formed between the orbiting scroll and the fixed scroll, may be formed to allow the orbiting scroll and the fixed scroll to be adequately attached to each other, thereby solving the limitations with respect to leakage and lubrication.
The back pressure chamber may be formed on a bottom surface of the orbiting scroll or a top surface of the fixed scroll. For convenience of description, the back pressure chamber formed on the bottom surface of the orbiting scroll and the back pressure chamber formed on the top surface of the fixed scroll may be referred to as a “lower back pressure type scroll compressor” and “an upper back pressure type scroll compressor”, respectively. The lower back pressure type scroll compressor has advantages in that the lower back pressure type scroll compressor has a simple structure, and a bypass hole is easily formed. However, as the back pressure chamber is formed on the bottom surface of the orbiting scroll, which performs the orbiting motion, the back pressure chamber may change in configuration and position according to the orbiting motion. As a result, the orbiting scroll may be tilted, causing vibration and noise. In addition, an O-ring provided to prevent the refrigerant from leaking may be quickly worn out. The upper back pressure type scroll compressor has a relatively complicated structure. However, as the back pressure chamber is fixed in configuration and position, the fixed scroll may not be tilted, and sealing of the back pressure chamber may be good.
The fixed scroll may be movably coupled to a main frame. The main frame refer to a part fixed to an inner wall of a casing that defines an outer appearance of the compressor. As the fixed scroll is movably coupled to the main frame, the fixed scroll and the orbiting scroll may be closely attached to each other by a force applied from the back pressure chamber.
FIGS. 1A to 1G are views illustrating a method of assembling a fixed scroll with a main frame according to a related art. FIG. 2 is a cross-sectional view of an assembly of the fixed scroll and the main frame which are assembled using the method according to the related art.
Referring to FIGS. 1A and 1B, an assembly 1 according to the related art includes a plurality of coupling members 6a, 6b, and 6c, a main frame 2, and a fixed scroll 3, which are assembled with each other by a guide pin 7. The plurality of coupling members 6a, 6b, and 6c include a first coupling member 6a, a second coupling member 6b, and a third coupling member 6c. The guide pin 7 may surround a lower portion of each of the coupling members 6a, 6b, and 6c. 
When the main frame 2 and the fixed scroll 3 are assembled with each other, a plurality of reference pins 5a and 5b to guide an assembled position may be used. The plurality of reference pins 5a and 5b include a first reference pin 5a and a second reference pin 5b. 
In detail, referring to FIG. 1A, the main frame 2 includes a plurality of frame holes 2a, into which the plurality of reference pins 5a and 5b or the plurality of coupling members 6a, 6b, and 6c are inserted. That is, the plurality frame holes 2a may include holes, into which the plurality of reference pins 5a and 5b are inserted, and holes, into which the plurality of coupling members 6a, 6b, and 6c are inserted. The fixed scroll 3 includes a plurality of first holes 4, into which the plurality of reference pins 5a and 5b are inserted, and a plurality of second holes 5, into which the plurality of coupling members 6a, 6b, and 6c and the guide pin 7 are inserted.
Hereinafter, a method for assembling the frame assembly 1 according to the related art will be described.
Referring to FIG. 1A, the fixed scroll 3 is disposed on the main frame 2 so that the plurality of frame holes 2a and the plurality of first and second holes 4 and 5 are aligned with each other. Also, each of the first and second reference pins 5a and 5b passes through the first hole 4 of the fixed scroll 3 and then is inserted downward.
When the first and second reference pins 5a and 5b are completely inserted, each of lower portions of the first and second reference pins 5a and 5b may be inserted into the frame hole 2a of the main frame 2. As described above, as the first and second reference pins 5a and 5b are inserted into the fixed scroll 3 and the main frame 2, the main frame 2 and the fixed scroll 3 may be fixed to or at predetermined positions without moving.
Referring to FIGS. 1B and 1C, in a state in which the first and second reference pins 5a and 5b are inserted, each of the first and second coupling members 6a and 6b passes through the second hole 5 of the fixed scroll 3 and then is inserted downward. Each of the first and second coupling members 6a and 6b is coupled to the frame hole 2a of the main frame 2.
A screw thread may be formed on each of the first and second coupling members 6a and 6b. Thus, each of the first and second coupling members 6a and 6b may be screw-coupled to the frame hole 2a of the main frame 2. Of course, a screw thread may be formed on an inner circumferential surface of the frame hole 2a. When the assembly of the first and second coupling members 6a and 6b is completed, the guide pin 7 may be disposed between the fixed scroll 3 and the main frame 2, in a state in which the guide pin 7 surrounds each of the first and second coupling members 6a and 6b. 
Referring to FIGS. 1D and 1F, in a state in which the assembly of the first and second coupling members 6a and 6b is completed, the second reference pin 5b may be separated. Also, a third coupling member 6c may be coupled to a position from which the second reference pin 5b is separated, that is, each of the first hole 4 of the fixed scroll 3 and the frame hole 2a of the main frame 2. That is, the second reference pin 5b may be separated, and then, the third coupling member 6c may be coupled to or at the separated position.
The third coupling member 6c passes through the second hole 5 of the fixed scroll 3, and then is inserted downward, like the first and second coupling members 6a and 6b. Also, the third coupling member 6c is screw-coupled to the frame hole 2a of the main frame 2. Referring to FIG. 1G, in a state in which the main frame 2 and the fixed scroll 3 are assembled with the plurality of coupling members 6a, 6b, and 6c, the first reference pin 5a may be separated last.
The frame assembly 1 assembled using the method according to the related art may have the following limitations.
As the plurality of coupling members 6a, 6b, 6c are assembled with the frame assembly 1 several times, the main frame 2 or the fixed scroll 3 may be twisted, or the coupled portion may be deformed whenever the plurality of coupling members 6a, 6b, 6c is assembled. In detail, referring to FIG. 2, the main frame 2 and the fixed scroll 3 may be assembled with each other by the first coupling member 6a. When the main frame 2 is assembled with the fixed scroll 3, fixed wrap 3a of the fixed scroll 3 may be closely attached to a head plate of orbiting scroll 8, and orbiting wrap 8a of the orbiting scroll 8 may be closely attached to the head plate of the fixed scroll 3.
When the main frame 2 and the fixed scroll 3 are assembled with each other by the above-described method, stress may be applied to the fixed scroll 3 in a predetermined direction by a coupling force of the first coupling member 6a. That is, the first coupling member 6a and the guide pin 7 may be closely attached to each other in a predetermined direction (a left direction in FIG. 2) within the second hole 5 of the fixed scroll 3. Thus, a deformed part or portion 3b may be formed in or at an inner circumferential surface of the second hole 5 of the fixed scroll 3 by the stress.
On the other hand, the inner circumferential surface of the second hole 5, which is disposed in a direction opposite to the closely attached direction may be spaced apart from the guide pin 7. That is, a space 7a may be defined between the inner circumferential surface of the second hole 5 and an outer circumferential surface of the guide pin 7.
As described above, in the state in which the main frame 2 and the fixed scroll 3 are assembled with each other, if the stress is applied to form the deformed portion 3b and the space 7a in the fixed scroll 3, the fixed scroll 3 may not easily move with respect to the main frame 2. Thus, the closely attached effect (a refrigerant leakage prevention effect) realized by the fixed scroll and the orbiting scroll due to the operation of the back pressure chamber may be reduced.
Also, when the main frame and the fixed scroll are assembled with each other using the method according to the related art, the plurality of coupling members have to be assembled through several processes. Also, as a complicated process for assembling the coupling member after the reference pin is separated has to be performed, productivity of the frame assembly may be deteriorated.